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The conclusions of the Gershgorin circle theorem are significantly extended for the special case of real matrices. The extended result is applied to the problem of the absolute stability of both continuous- and discrete-time Lur'e systems containing sector nonlinearities. Specifically necessary conditions for the existence of common unic Lyapunov functions are presented in the form of constraints...
An analogue high-pass single-pole filter with a 0.05Hz cut-off frequency has been used for decades as the comparison milestone for the low frequency performance of electrocardiographs. The aim of this work is to prove that it is possible to design other analogue high-pass filters that allow undistorted recordings of the ECG signal and yet have better rejection characteristics than this reference first...
This paper first presents two wave models of non-uniform, lumped, chain-like systems, one shunt and one series. They consist of interlinked wave transfer functions, which turn out to be somewhat arbitrary. The series and shunt wave models are mutually consistent and can be combined into a single, composite wave model. Control strategies based on these wave ideas are then presented. They use wave models...
We identify two major difficulties with the formulation of a rigorous mathematical theory for the Empirical Mode Decomposition (EMD): a) the concept of the envelope is not well defined, and b) the output of the EMD fails a very simple consistency criterion.
Traditional methods of energy expenditure estimation, in the free-living environment, attempted using accelerometry operate without knowledge of the slope of the terrain which is being traversed. The ability to recognise the gradient of the walking surface will most likely improve upon these simplistic energy estimates. This paper expands upon previous work in this area, and investigates the benefit...
This paper describes a study which was carried out to determine an optimally performing classification algorithm for the problem of subject independent gait pattern classification. The study utilised a frequency domain based feature vector based on the concept of cepstral coefficients whose generation methodology was optimised in terms of overall system recognition rates. The performance of a number...
When a signal is recorded that has been physically generated by some scattering process (the interaction of electromagnetic waves with an inhomogeneous dielectric, for example), the ‘standard model’ for the signal (i.e. information content convolved with a characteristic Impulse Response Function) is usually based on a single scattering approximation. An additive noise term is introduced into the...
Automatic music transcription is a widely studied problem, Typically, recordings that are used for transcription are taken from standard instruments, in the case of electric stringed instruments—such as the electric guitar—the recordings are captured from a standard pick-up, which unwantedly mixes the signals from each string and complicates subsequent analysis. We propose an approach to electric...
The frequency response characteristic of a through transmission Capacitive Ultrasonic Transducer (CUT) system is quite often dominated by membrane resonances of the transmit and receive devices and transmission channel distortion. Simple analog filtering stages may be appropriately designed to compensate for the most pronounced of these channel effects. In many ultrasonic inspection applications a...
The modelling of uncertain and dynamic environments is an important and challenging problem in mobile robotics. Nonlinear dynamic systems can be represented as Takagi-Sugeno (T-S) fuzzy models, with linear or affine consequence. This paper proposes a novel method of object tracking in cluttered environments for mobile robots using T-S fuzzy models. The model has been tested on a Patrolbot which tracks...
The majority of computer vision applications assume that the camera adheres to the pin-hole camera model. However, most real optical systems will introduce some undesirable effects, rendering the assumption of the pin-hole camera model invalid. By far the most evident of these effects is radial distortion, particularly in fish-eye camera systems where the level of this distortion is relatively extreme...
An FPGA-based implementation of a pedestrian detection system using thermal infrared imaging is presented. The main feature of the processing platform is its ability to detect pedestrians at frame-rate from an infrared video stream. It is designed as a stand alone processing unit, supporting security systems in low visibility conditions. The processing unit digitizes a video source from a thermal...
Chaos-based encryption has suggested a new and efficient way to deal with the problem of fast and highly secure image encryption. In this paper, a new chaotic key generator for image encryption and its FPGA implementation based on a chaos switching rule between Lorenz's and Lü's non-linear systems is proposed for designing a real-time secure symmetric encryption scheme. The originality of this new...
One requires assumptions about signals in order to sample them such that the analog signal may be recovered from its samples. The assumption in Shannon sampling can be thought of as the signal's Wigner-Ville distribution function (WDF) being confined to a strip centered on the time axis. Several other sampling theorems assume a signal's WDF is confined to a strip about some other straight line through...
Recent research into urban analysis through the use of mobile device usage statistics has presented a need for the collection of this data independently from mobile network operators. In this paper we propose that cumulative received signal strength indications (RSSI) for overall mobile device transmissions in an area may provide such independent information. A process for the detection of high density...
A multi-sensor, multi-modal sensor node for human and vehicle activity monitoring is designed and developed. As a first step to achieve our objective, we have used a dual pyroelectric IR (PIR) sensor system for human activity monitoring. The sampled data from two PIR sensors, under laboratory conditions, is first processed individually to determine the event window size, which is then fed to simple...
This paper presents a study of the performance of three antennas for ultra wideband radio ranging systems. By using different pulse types, the performance of the antennas is measured and quantified by using the Fidelity Factor.
A variation of an existing technique for movement artifact detection in single lead ECG signals acquired in the unsupervised telehealth environment is examined. The impact on heart rate (HR) estimation is investigated using this artifact detection technique to remove noisy sections of signal. The estimated artifact masking and HR values are compared to a gold standard scoring, performed by consensus...
A computational model of the auditory periphery enables faster investigation of new signal processing algorithms for hearing aids. This paper presents a study of the degradation of auditory nerve (AN) responses at a phonetic level for a range of sensorineural hearing losses. The AN model of Zilany & Bruce was used to compute responses to a diverse set of phoneme rich sentences from the TIMIT database...
Elastography and strain imaging often use ultrasound to measure mechanical properties of soft tissues. These techniques generally examine radiofrequency signals from an ultrasound scanner. This study investigates the feasibility of strain estimation directly from an ultrasound B-mode image, using segmentation and shape analysis. Several thousand computer generated tissue mimicking phantoms with stiff...
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